1. Field of the Invention
This invention relates to a method for continuously molding a surface fastener, which has a multiplicity of engaging members on a surface of a plate-like substrate sheet, by extruding thermoplastic resin.
2. Description of the Related Art
The technology of extruding a substrate sheet using thermoplastic resin and, at the same time, molding hooks on one surface of the substrate sheet is already known by, for example, WO87/06522. The molding method disclosed in this publication comprises extruding molten thermoplastic resin onto a circumferential surface of a drum-shape die wheel, in which a multiplicity of mold discs and a multiplicity of spacer plates are laminated alternately, filling the hook-forming cavities of the mold discs with the resin while pressing the resin on the drum surface to form a substrate sheet, and pulling molded hooks out of the cavities along with the substrate sheet in timed relation to the rotation of the drum while the resin is cooled. The mold disc has in one side surface hook-shape cavities extending radially from the circumferential surface toward the center and spaced circumferentially at predetermined distances. The side surfaces of the spacer plate are flat. The reason why the spacer plate is needed is that the cavities of the whole shape of the hook cannot be formed in a single mold.
According to the surface fastener manufacturing method disclosed in the above-mentioned publication, since the surface fastener is merely molded continuously of thermoplastic resin, it would be extended due to a tension exerted on the surface fastener when it is cut into pieces, thus causing dimensional errors in the products. Further, when the resulting surface fastener is attached to a garment by sewing, the surface fastener would have cracks due to the sewing needle so that it cannot be sewn to the garment.
With the foregoing problems in view, it is an object of this invention to provide a molding method for manufacturing a surface fastener effectively and simply which is free of extension though molded of thermoplastic resin by extrusion, is free from any crack during sewing and is stable in shape.